This article is from the Mac Programming FAQ, by Jon Watte email@example.com with numerous contributions by others.
Good question. Apple, in the guise of Jim Luther of Mac Developer
Technical Support, has written a library called MoreFiles, which not
only provides a high-level interface to low-level file stuff, but
provides FSSpec glue for Systems below 7. MoreFiles is available on the
Developer CD's (see above) and also at Appple's developer ftp site.